Gas turbine



J. A. RAVVLINS Aug. 5, 1952 GAS TURBINE 2 SHEETS-SHEET l Original Filed Oct. 5, 194

l lllll llll s W W L w T4 TD KAN N R EA .0 w n f m 2-s1-1EETs-sI-IEET 2 GAS TURBINE J. A. RAVVLlNS INVENTOR JOSEPH A RAWL/NS BY/ W ATTORNEY Original Filed Oct. 5, 1945 Aug. 5, 1952 9 0% mm wm Patented Aug. 5, 1952 GAS TURBINE Joseph A. Rawlins, Tenafly, N. .1 assignor, by mesne assignments, to The Sperry Corporation,

a corporation of Delaware Original application October 5, 1945, Serial No. 620,523,now Patent No. 2,511,543, dated June. 13, 1950. Divided. and this application September 27, 1947, Serial No. 776,559

2 Claims. 1

This invention relates to gas turbines and more particularly to mechanism for imparting a limited axial oscillating movement to a turbine shaft.

An object of the invention is to provide mechanism responsive to the gas discharge pressure from the turbine, for automatically producing the oscillating movement.

Another object is to provide means for controlling the axial position of the turbine shaft without physical frictional contact with the Totating parts.

Another object is to provide a novel and improved device of the type above indicated.

Various other objects and advantages will be apparent as th nature of the invention is more fully disclosed.

This application is a division of my co-pending application, Serial No. 620,523, filed October 5, 1945, for Gas Lubricated Bearing, now Patent No. 2,51 ,543, issued June 13, 1950. I

The present invention is particularly app1icable to spindles for high speed tools such as small diameter grinding wheels which may operate at speeds of the order of 50,000 R. P. M. The bearing may hav a clearance of the'order of .0001 inch so as to position the tool accurately and cause it to operate without'wabble or side play.

In accordance with the present invention the gas is discharged at the two sides of the turbine rotor into channels formed between the rotor and a pair of side plates. The relative gas pressures on the two sides of the rotor are a function of the clearance of the side plates. 'When the clearances are equal the pressure on the two sides of the rotor is equalized and no axial movement takes place. However, by shifting one of th side plates so as to increase or decrease the clearance the pressure balance is upset and the differential air pressure acting on the two sides of the rotor causes axial movement thereof. In one embodiment the position of the sideplates is varied when the rotor reaches its limiting axial position so as to automatically cause the rotor to shift axially first in one direction and then inthe other.

Although the novel features whicha'r believed to be characteristic of this invention are pointed out more particularly in the claims appended hereto, the invention itself may be better understood by referring to the following description taken in connection with the accompanying drawings in which specific embodiments thereof have been set forth for purposes of illustration.

Fi 1 is an end e evat n Of an a lubricated spindle including mechanismfor causing axial oscillation of the spindle;

Fig. 2 is a side elevation of the spindle of Fig. 1;

Fig. 3 is a vertical longitudinal section thereof taken on the line 33 of Fig. l; and

Fig. 4 is a section similar to Fig. 3 but showing the spindle in a different axial position.

Referring to the drawings, the invention is shown as applied to a spindle l0 carrying a tool, shown as a grinding disc I l,'mounted on a shank i2 which is secured to the spindle ID by suitable means shown as a set screw l3. The spindle I0 ,is provided with an enlarged cylindrical bearing section it which is journalled in bearings surfaces I 5 and I 6 formed in upper and lower bearing blocks ll and I8, respectively.

The lower bearing block [8 constitutes a fixed support and is mounted by any suitable means not shown. The upper bearing block I! is accurately positioned transversely of the lower bearing block 18 betweenclips l9. Studs 20 are secured inthe lower bearing block 18 and extend through holes in the upper bearing block I! so as to positionlthe upper bearing block axially relative to the lower block and'to allow vertical movement of theuppe'r block. The upper bearing block H is yieldably held against the lower bearing block l9 by means of slotted leaf springs 2| which engage grooves 22 in the studs 20.

The bearing blocks l1 and I8 are formed with cylindrical chambers 25 extending axially of the blocks between the bearing surfaces l5 and H5. The radius of the chambers 25 is such as to provide substantial clearance for the bearing section M of the spindle. Horizontal slots 26, formed half and half in the two bearing blocks, extend from the chambers 25 to the outside of the blocks between shoulders 21. The shoulders 21 form th contacting surfaces for the two bearing blocks and are accurately finished to determine the minimum bearing clearance. The clearance between the bearing section I4 and the bearing surfaces I5 and i6 is of the order of .0001 inch when the shoulders 21 are in contact. This clearance, however, is permitted tobe increased by'separating the bearing blocks I! and [3 against the pressure of the springs 2|.

Axial channels 28 (Fig. l) are formed'half and half in' the bearing blocks l1 and [8 along the parting line so that the bearing surfaces I5 and it are removed for ashort distance each side of the parting line.

The spindle I0 is shown as rotated by an air turbine comprising a rotor 30 enclosed in a housipg 3i and having suitable driving vanes 32. The

housing 3| includes an air chamber 33 and admission ports 34 by which air is supplied to the vanes 32 in the usual manner for causing rotation of the rotor. The rotor 30 is mounted upon an extension 35 of the spindle l which is of reduced section, ,and is held against the enlarged bearing section M by means of an annular sleeve 3'! which is mounted on the extension 35 of the spindle and has an annular rim 38 of the same diameter as the bearing section l4. Air is discharged from the turbine through openings 39 formed in the housing 3| around the rim 38 and around the bearing section l4. Baflle plates 40 and 82 are spaced from the two sides of the housing 3| in a manner to control the exhaust air pressure on the two sides of the rotor.

A disc 45 is attached to the end of the extension 35 by means of a screw 46. The housing 3| is secured by a screw 18 to a slide 6|. The slide 6| is provided with inclined surfaces 62 which are slidably held in gibs 63' to permit axial adjustment. The slide BI is secured in adjusted position by means of a clamping screw 84. The slide 6| is mounted for adjustment by means of an adjusting screw 65' which is threaded in a bracket 66 formed as a part of the lower bearing block I8 and is adjusted by a hand knob 61. A spring 88 holds the slide 6| against the end of the screw 65. Compressed air is supplied to the turbine through a duct 69.

The disc 45 is engaged by fingers and 15 of a yoke 11 which is pivoted on a bracket 18 carried by an arm 60 attached to the slide 8|. The plate 48 is shown as rigidly secured by screws 88 to the housing 3|. The other plate 82, however, is loosely held on pins 83 and is hung from a supporting pin 84 so that the plate 82 may pivot about the pin 84 and allow the lower portion of the plate to' approach or recede from the housing 3|.

The position of this lower portion of the plate 82 is controlled by an arm 85 carried by the yoke El and engaging a cam plate 86 attached to the plate 82 and arranged so that when the spindle i8 is moved to the right as shown in Figs. 2 and 3 the disc 45 engages the finger 16 of the yoke TI and causes pivotal movement of the yoke which retracts the arm 85 from the cam 86 and leaves the plate 82 free to swing away from the housing 3|. When the spindle I8 is in its lefthand position as shown in Fig. 4, the disc 45 engages the finger 15 of the yoke and causes pivotal movement of the yoke to bring the arm 85 into engagement with the cam plate 86 thereby forcing the plate 82 toward the housing 3|, The arrangement is such that with the plate 82 in the position shown in Fig. 4 the clearance between the plate 82 and the housing 3| is less than the clearance between the stationary plate 40 and the housing 3|, but with the plate 82 released as shown in Figs. 2 and 3 the clearance between the plate 82 and the housing 3| is greater than that between the stationary plate 48 and the housing 3|.

In the operation of this device, the spindle H) is rotated by the compressed air turbine in a manner which will be readily understood. The lubricant for the bearing surfaces I5 and I6 constitutes air which is compressed between the bearing surfaces I5 and I6 and the bearing section l4 of the spindle in due solely to the relative rotation of the parts. The air is accordingly maintained at a pressure which is above that of the surrounding atmosphere due solely to the rotation of the parts themselves.

The air pressure on the two sides of the rotor 30 is controlled by the clearance between the plates 40 and 82, respectively, and the housing 3| because the air discharged from the turbine passes outwardly through the openings 39 and then is exhausted to atmosphere through the passages between the plates 40 and 82, respectively, and the housing 3|, and is also exhausted between the plates 40 and 82 and the surface of the bearing section 4 and of the rim 38. When these clearances are equal the air pressures on the two sides of the rotor are equalized and the rotor remains in a central position. However, when the plate 82 is released as in Figs. 2 and 3, the pressure on the left-hand side of the rotor becomes less than the pressure on the right-hand side of the rotor and the latter is driven by this pressure differential toward the left-hand side of the housing 3| into the position shown in Fig. 4.

When this position is reached, the arm 85 is actuated to engage cam 86 and shift the plate 82 toward the housing 3| so that the clearance between the plate 82 and the housing 3| becomes less than that between the plate 40 and the housing 3|. Air pressure is thus built up on the left-hand side of the rotor which causes the rotor to shift axially to the right-hand side of the housing into the position indicated in Fig. 3. In that position the arm 85 is again actuated to release the plate 82 and the operation is repeated.

The turbine rotor 30 and the spindle l8 are thus caused to oscillate in an axial .direction. Such axial operation of the grinding disc [I may be useful, for example, in polishing or grinding surfaces to a smooth finish where it is desired to avoid any marks which might otherwise be produced by the grinding wheel itself.

Although certain specific embodiments of the invention have been shown for purposes of illustration, it is to be understood that the invention is capable of various uses and that changes and adaptations may be made therein as will be readily apparent to a person skilled in the art. The invention is only to be restricted in accordance with the scope of the following claims.

What is claimed is:

1. In combination with a spindle mounted for free rotary and axial movement, a gas driven turbine having a rotor with peripheral vanes mounted on said spindle to rotate the same, a turbine housing having a peripheral wall and side walls forming gas chambers on each side of said rotor, ports supplying gas peripherally to said vanes, said side walls having gas discharge ports from each of said chambers, plates mounted respectively over each of said side walls and spaced therefrom to provide passages for the exhaust of gas discharged from said discharge ports, one of said plates being adjustable toward and from its side wall to vary said passage and produce a pressure differential on the two sides of said rotor and efiect axial movement of the rotor and spindle, a member mounted for back-and-forth movement and disposed to engage and position said one plate relative to its side wall, and actuating means on the spindle operatively engageable with the member.

2. In combination with a spindle mounted for free rotary and axial movement, a gas driven turbine having a rotor with peripheral vanes mounted on said spindle to rotate the same, a turbine housing having a peripheral wall and side Walls forming gas chambers on each side of said rotor, ports supplying gas peripherally to said vanes, said side walls having gas discharge ports from each or said chambers, plates mounted rejection on the spindle engageable with the other spectively over each of said side walls and spaced arm to oscillate the member. 1

therefrom to provide passages for the exhaust JOSEPH A. -RAWLINS. of gas discharged from said discharge ports, one of said plates being-adjustable toward and from 5 7 REFERENCES CITED v its Side Wall o y Said P age and p o a The following references are of record in the pressure difierential on the two sides of said rotor file of t patent: M

and effect axial movement of the rotor and spindle, a bell-crank oscillatory member having a UNITED STATES PATENTS cam on one arm engageable with the said one 10 Number Name Date plate as the member oscillates to control its 2,332,526 White A 1 1 5 spacing from its side wall, and an actuating pro- 

